#bg {
    background: url('../image/xmu2.jpg') no-repeat bottom right;
    height: 100%;
    right: 0;
    opacity: 1;
    position: fixed;
    top: 0;
    background-size: cover;
    width: 736px;
    filter: blur(3px)
}

@media screen and (min-width: 736px) {
    @keyframes bg {
        0% {
            transform: translate3d(0, 0, 0);
        }
        50% {
            transform: translate3d(calc(100vw - 3 * 100vh), 0, 0);
        }
        100% {
            transform: translate3d(0, 0, 0);
        }
    }

    #bg {
        animation: bg 60s ease-in-out infinite;
        backface-visibility: hidden;
        background: url('../image/xmu.jpg') no-repeat bottom left;
        height: 100%;
        left: 0;
        opacity: 1;
        position: fixed;
        top: 0;
        background-size: contain;
        width: 3000px;
    }
}